The present invention relates to a storage system and a method of storage system path control.
For example, in order to handle large volumes of various types of data in government, public offices, local authorities, industry, and educational institutions and the like, comparatively large-scale storage systems are used in management of data. These storage systems are, for example, comprised of disk array devices and the like. Since a disk array device is comprised of a plurality of storage devices arranged in an array, for example, a storage area based on a RAID (Redundant Array of Independent Disks) is provided.
At least one logical volume (logical unit) is formed in the physical storage area provided by the group of storage devices, and this logical volume is provided to the host computer (that is to say, the database program running on the host computer). By sending the prescribed command, the host computer (hereafter referred to as the ‘host’) can write data to, and read data from, the logical volume.
Data to be managed increases daily in association with development of the information society. Storage devices of greater performance and capacity are therefore required, and storage systems employing a plurality of storage devices are sometimes configured in response to these market demands.
When configuring storage systems employing a plurality of storage devices, a method whereby existing old types of storage device are replaced by new types of storage device is known (see Published Japanese Translation No. H10-508967 of PCT International Publication). In the conventional technology disclosed in this document, a time zone of low load is determined, and data on the existing storage device is migrated to the newly installed storage device.
The technology disclosed in the afore-mentioned document simply replaces the existing storage device with a newly installed storage device. In this document, one storage device uses the storage resources of another storage device in an autonomous manner, and thus the effective use of overall storage resources of the storage system is not considered.
As disclosed in the afore-mentioned document, when completely migrating data from an old type of storage device to a new type of storage device, the functions and performance of the new type of storage device may be used. However, when data has been completely transferred, the old type of storage device is wasted, and the old type of storage device cannot be used effectively.